I found it a decent length, really. With a game like Canis Canem Edit, I take my time to bask in the surroundings, enjoy the missions fully etc. Instead of rushing through it. The first chapter for me was long (Because I just messed about for a bit, etc.) The Other Chapters were slightly shorter. But the storyline and missions kept me wanting to redo them, so I just saved before the Greatest missions.
Exempli Gratia, Total Mayhem, The Candidate, Halloween, the whole nerd vs. Jocks chapter.